Differential Mode Noise Research Articles

A Dithering Technique for Mitigation of Differential Mode Noise of SiC MOSFET based Buck converter

A Dithering Technique for Mitigation of Differential Mode Noise of SiC MOSFET based Buck converter

A PCB-Incorporated Inductor Based Filter Design Solution for Differential Mode Noise of 3-Phase SiC-MOSFET Based VSI

A PCB-Incorporated Inductor Based Filter Design Solution for Differential Mode Noise of 3-Phase SiC-MOSFET Based VSI

Estimating the Differential Mode Noise of a DC-DC Converter

Electromagnetic noise emission is inevitable in a DC-DC converter due to the employed switching technique. In low frequency, the noise propagating through cabling and conductive media is called a conducted emission. A conducted emission consists of differential mode and common mode noise. It is advantageous to know an estimate of emission level for each mode during the design phase so that suitable mitigation can be included earlier.. This paper aims to focus on a method to estimate the differential mode noise emission of a DC-DC converter. The estimation is computed using the input capacitor complex impedance and the current that flows through it. As a study case, a boost and buck converters are used for evaluation. The estimation and measurement results are compared. Despite differences at some frequencies, the estimated and measured results generally agree well. Because of its simplicity, the proposed method can be used as a practical tool in the EMC aspect of DC-DC converter design.

Comprehensive Conducted Emission Analysis of the Three-Phase and Single-Phase LLC Resonant Converters for EV Application

Resonant <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter is a preferred candidate for emerging electric vehicle (EV) applications, thanks to its high efficiency and high power density characteristics, which are achieved due to high switching frequency and soft-switching operation. On the other hand, planar transformers (PTs) for EVs offer power density in a small package and withstand vibrations. However, large parasitic capacitance is a characteristic of PT, which along with the large <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> of the converter leads to severe conducted emission problems. Therefore, multifold complicated and bulky electromagnetic interference (EMI) filters are required to suppress conducted noise and meet the requirements of the relevant standards. In this article, a comprehensive analysis has been conducted to model and study both single-phase and three-phase <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converters from a conducted noise perspective. With this study, a better understanding of the EMI behavior of these converters can be obtained. Owing to the symmetrical design of the three-phase converter, several harmonics cancel out each other, resulting in lower common-mode (CM) emissions. It is also shown that differential-mode (DM) current generated from the three-phase converter contains lower peak amplitude at high frequency. For comparison purposes, two prototype converters based on the conventional single-phase and the three-phase configuration are fabricated and their conducted emissions are measured and compared experimentally. Simulation and experimental results verify that the three-phase converter effectively suppresses CM and DM noise by a considerable amount.

Estimation of Common Mode noise and Differential Mode noise generated by DC-DC Power Converters

The study contains a review of the body of knowledge regarding differential mode (DM) and common mode (CM)noise and how they affect power converter performance. With an emphasis on practical application, this work seeks to give an estimation of differential mode (DM) and common mode (CM) noise for cutting-edge DC-DC power converters such as Zeta converters, Single Ended Primary Inductance Converters (SEPIC), and Cuk converters. Active noise separators and Differential mode noise separators are used as a measurement technique to quantify DM and CM noise, considering a number of variables including input voltage, output voltage, load current, and switching frequency. By using filtering techniques, DM and CM noise can be reduced. Both CM noise and DM noise are created by the Zeta converter at 114 dBµV and 108 dBµV, respectively. CM noise from the SEPIC converter is 119 dBµV, and DM noise is 114 dBµV. With values of CM noise 98 dBµV and DM noise 106 dBµV, Cuk converter produces less noise when compared to Zeta and SEPIC converter. The results show that power converters can generate DM and CM noise, and that this noise is over the Comité International Special des Perturbations Radioélectriques [CISPR] limit line. The conducted emission range for various electronic devices is provided by this standard. This study provides useful insights for power converter designers and engineers to optimize the performance of their systems in practical applications.

Innovative measurement and noise reduction of voltage coupling in shielded cables for enhanced signal integrity

The reliable transmission of electrical signals through shielded cables in the presence of electromagnetic interference (EMI) remains a critical challenge for signal integrity. This paper presents a novel and comprehensive approach for measuring and reducing voltage coupling in shielded cables connected to a shielded room from a waveguide. Additionally, we introduce an innovative active EMI filter to effectively mitigate common-mode (CM) and differential-mode (DM) noises, thereby enhancing the overall signal quality. To address the issue of voltage coupling, an open circuit method with a transmission line is considered for the measurement of output voltage at the end of the shielded cable. In order to assess the impact of EMI on transmitted signals, we utilize a state-of-the-art noise separator that enables precise differentiation and characterization of CM and DM noise components. This analysis provides valuable insights into the overall noise profile, guiding the subsequent steps toward noise reduction. An active EMI filter was designed to effectively attenuate the unwanted noise. The filter intelligently targets and mitigates both CM and DM noises, resulting in improved signal integrity. The experimental setup encompasses a shielded room, shielded cables, a waveguide, and the equipment. The obtained output voltage from the shielded cable is 495 V. It is given as an input to the equipment (Cuk converter). The noises are generated when the input voltage is given; the noises are separated by using a noise separator. CM noise obtained at the output of an active noise separator is 118.8 dBµV. DM noise obtained at the output of a differential mode noise separator is 115.8 dBµV. With the active EMI filter, we achieve remarkable reductions in CM and DM noise levels. After adding a filter to the circuit, the noises are reduced below the limit line according to the International Special Committee on Radio Interference standard; the CM noise is 44.8 dBµV and the DM noise is 47.8 dBµV.

Three-Phase Modal Noise Analysis and Optimal Three-Phase Power Line Filter Design

Conducted emissions (CE) for three-phase systems are becoming an increasing concern due to the recent exponential growth of three-phase applications, especially linked to the automotive sector. The problem arises because electromagnetic compatibility (EMC) standards only define the methodology to measure the CE generated by the equipment under test (EUT), and they do not provide sufficient information to design a power line filter (PLF) in case of non-compliance. Hence, the design of an optimal PLF is a very difficult task for engineers. The unclear methodology to be followed, unknown load impedances, inadequate equipment, and lack of knowledge of the modal noise are all different reasons that contribute to increasing the PLF design complexity. Common mode (CM) and differential mode (DM) decomposition and PLF design techniques for single-phase EUTs are well discussed and studied in the literature, but the same cannot be stated when it comes to three-phase PLF design. The objective of this paper is to clarify how modal noises behave in a three-phase system and to propose a clear methodology which can be followed to design an optimal three-phase PLF. Additionally, this paper analyses and discusses the modal noises’ intrinsic behavior and provides an understanding of how the PLF components behave when subjected to either a CM or DM noise. Finally, a methodology to design a three-phase PLF, based on accurate insertion loss (IL) estimations and S-parameter measurements, is used to determine the optimal PLF. This approach is tested and validated.

Current Zero-Crossing Prediction-Based Critical Conduction Mode Control of Totem-Pole PFC Rectifiers

Critical conduction mode (CRM) is widely used in totem-pole Boost power factor correction converters due to its compatibility with soft-switching and high switching frequency. Conventionally, a current sensor or zero-current detector is required to realize CRM operation. The system performances highly rely on the behaviors of peripheral circuits. Additional power loss and delay are also introduced. Moreover, the inductor current contains obvious differential mode noise, which brings interferences to the sensing signals. To address this issue, a novel CRM realization method is proposed. It utilizes an inductor current estimator model to estimate the averaged current and to predict the current zero-crossings. The noisy sensing signal is replaced by estimated values. Therefore, the zero-current detection circuit is removed, which simplifies the peripheral circuit design. Valley-switching and zero-voltage switching can also be achieved. Operation principles, digital implementation, and error suppression of the proposed control are analyzed. The proposed concepts are validated on a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\rm{550}~W$</tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$150\mathrm{k}Hz-1.6\mathrm{M}Hz$</tex-math></inline-formula> , GaN-based prototype. Experimental results record 98.96% peak efficiency with a 0.9972 power factor.

Improvement of high-power thyristor trigger circuit with switching-mode power supply for differential-mode noise reduction

This paper focuses on the differential-mode (DM) noise of high-power thyristor (HPT) trigger circuit with switching-mode power supply (SMPS) in capacitive pulsed power supply (CPPS). Parasitic parameter models of components are discussed and analyzed. Based on the parasitic parameter models of components, a DM noise prediction model of HPT trigger circuit with SMPS is developed. The generation mechanism and propagation paths of the DM noise in HPT trigger circuit with SMPS are investigated. To reduce the DM noise, a capacitive SMPS technique is adopted in the HPT trigger circuit with SMPS. Simulation results validate the theoretical analysis.

A Unified Differential Mode Noise Estimation Method and Filter Size Comparison in Single-Phase Multileg and Multilevel Totem-Pole PFC Converters

Wide band-gap power devices have enabled single-phase totem-pole (TP) power factor correction (PFC) converter designs to be switched at several tens of kHz under hard-switching and hundreds of kHz under soft-switching. It is straight-forward to analyze and compare the volume of boost inductor for TP PFC converters having multi-leg and multi-level configurations operating under continuous-conduction-mode (CCM) and critical-conduction-mode (CrM) at various switching frequencies; however, the impact of topology and switching frequency selections remains unchallenged for generated differential mode (DM) noise. This paper proposes a unified and generalized DM noise estimation method for multi-leg, and multi-level TP PFC converters operated under both CCM and CrM operation modes. The method has been verified with simulation results obtained from various TP PFC topologies, as well as experimental results obtained from single-leg CCM and 4-Level CCM TP PFC converters. The empirically determined boxed sizes of DM filters have been compared among various TP PFC topologies, and the best switching frequency for each topology has been determined with the integration of boost inductor volume comparison.

A Selective Common Mode Noise Mitigation Method Using Phase-Shifted Modulation for Four-Switch Buck–Boost DC/DC Converter

Wide bandgap (WBG) power devices can work at higher switching frequencies compared to silicon competitors. It helps reduce the volume of passive components but brings more serious electromagnetic interference (EMI) noise issue. The increased noise filtering requirements may restrict the power density improvement. This study discusses the conducted EMI issue and noise filtering in the four-switch buck-boost DC/DC converter (FSBB). The differential mode (DM) and common mode (CM) noise model embedded with noise sources features are derived and analyzed. It is found that modifying the spectral distribution of the CM noise is a challenge when the duty cycles are fixed by voltage gain. Inspired by the CM model, a phase-shifted modulation method is proposed to achieve selective CM noise mitigation. The recommended operating range and the implementation process are presented. The theoretical modeling and the proposed method are verified through a FSBB converter with 48V input and 100kHz switching frequency. And experimental results validate that the proposed method can achieve 30% volume reduction of the CM filter.

Characterization and Mitigation of Conducted Emissions in a SiC Based Three-Level T-Type Motor Drive for Aircraft Propulsion

This paper presents the full-scale high power inverter design considerations that are needed for minimum conducted noise propagation throughout the system. Specifically, system design issues pertaining to high current and high altitude, high switching transients during commutation process, ribbon cables for high-speed signal transmission, strict conducted emissions requirements and motor side bearing/leakage currents are discussed. Based on the underlying deficits for high power motor drives, layout and circuit design methodologies are proposed to tackle such problems, while keeping costs at a bare minimum. Subsequently, modeling and prediction of common-mode (CM) and differential-mode (DM) noise is made possible using accurate lumped inverter and filter models, allowing for a better understanding of the sensitive components contributing to peak CM-DM noise. A high power (211 kW) rated three level T-type inverter prototype is used to demonstrate the viability of the proposed design techniques for reliable system operation and conducted electromagnetic interference (EMI) emissions mitigation.

Analysis of Common-Mode Noise and Mixed-Mode Differential-Mode Noise in Dual Active Bridge Converter

The dual active bridge (DAB) converter is one of the widely explored topologies in recent years due to its remarkable features, such as inherent soft-switching characteristics, galvanic isolation, and high power density. However, the conducted electromagnetic interference (EMI) analysis of the DAB converter is seldom reported. In this article, the common-mode (CM) and the differential-mode (DM) equivalent circuits of the isolated DAB converter are presented to understand the propagation mechanisms of the conducted EMI noise in the converter. In particular, the mixed-mode DM (MMDM) noise component of the DM noise is quantified for the DAB converter. Furthermore, an experimental measurement method based on an external impedance-matched circuit is proposed to quantify the DM current due to capacitive coupling between the primary and secondary windings of the transformer. The quantified MMDM noise and the DM noise through the transformer are estimated using the proposed equivalent circuits in MATLAB-Simulink and validated experimentally on a prototype DAB converter.

Active noise reduction for a differential Helmholtz photoacoustic sensor excited by an intensity-modulated light source.

A highly sensitive differential Helmholtz photoacoustic sensor with active noise reduction was reported. Coupled to one cavity of the photoacoustic cell, an intensity-modulated excitation light would reflect multiple times to produce photoacoustic signal, and meanwhile cause the solid-state photoacoustic effect forming differential mode noise with the frequency same as the photoacoustic signal, which could not be suppressed by conventional differential technology. Wavelength modulation technology is a splendid method to restrain this effect, which is not suitable for light sources with not adjustable wavelength. To suppress this kind of noise, an intensity-modulated compensation light was coupled to another cavity, whose central wavelength was at the non-absorption line of the measured gas. The compensation light was of the same frequency, phase, and power as the excitation light, by which the solid-state photoacoustic effects were produced to form destructive interference called active noise reduction. The experiment results showed that the active noise reduction significantly improved the signal-to-noise ratio and signal-to-background ratio. Compared with the differential, the differential with active noise reduction improved signal-to- noise ratio by about 1.2 times and signal-to-background ratio by about 9.4 times. When low-power near-infrared lasers were employed as the two light sources, the minimum detection limits for acetylene and methane reached 21 and 200 ppb, respectively.

Enhanced Impedance Measurement to Predict Electromagnetic Interference Attenuation Provided by EMI Filters in Systems with AC/DC Converters

Due to the widespread integration of renewable energy sources connected to AC and DC power systems by means of power electronics converters, electromagnetic noise propagates along lines, and metallic earth-return structures. EMI filters are commonly used to mitigate the common mode and differential mode noise at the interface of distribution lines, and their suppression characteristics are usually assessed in standard test setups, the impedances of which are, however, scarcely representative of real-world applications. In this paper, an online, inductively coupled impedance measurement method is proposed. A sensitivity analysis to highlight the benefits of the proposed setup and experimental verification is performed. The proposed method enables non-intrusive impedance measurement in energized systems, including power converters. These measures, in turn, allow the evaluation of modal insertion losses of EMI filters in real-world operating conditions. The three-phase example considered in this study shows significant deviations from manufacturer specifications, thus justifying the need for more advanced estimation techniques.

High-Frequency Modeling of Delta- and Star-Connected Induction Motors

In this article, a high-frequency (HF) six-port delta- and star-connected three-phase induction motor model is proposed. The model consists of multistage RLC circuits, which include the mutual inductances between the phases. The three-phase HF motor model is derived from common-mode (CM) and differential-mode (DM) equivalent circuits, which are extracted from CM and DM measurements on the motor. A methodology is developed to consider the nonlinear DM inductance effect in the low-frequency (LF) range. The per-phase circuit is symmetric concerning the begin and end points. This symmetry allows us to connect a star configuration into a delta configuration by simply changing the phase connections of the proposed three-phase circuit without recalculating the parameters and vice versa. The three-phase motor model is eventually combined with external circuitry and simulated by a standard circuit solver. The proposed model allows impedance predictions with good accuracy up to 100 MHz. The method is verified with two induction machines, which have 3- and 11-kW rated powers. The proposed HF six-port three-phase motor model can be used for decoupled CM and DM noise predictions as well as for six-port mixed-mode noise prediction.

Impact of Motor Stator Winding Faults on Motor Differential-mode Impedance and Mode Transformation

Motor impedance and mode transformation have significant effects on the electromagnetic interference (EMI) generated in motor drive systems. Stator winding faults commonly cause motor failure; however, in their early stages, they may not affect the short-term operation of the motor. To date, EMI noise under the influence of premature stator winding faults has not been adequately studied, particularly the differential-mode (DM) noise due to the common-mode (CM)-to-DM transformation. This study investigates and quantifies the influence of stator winding faults on the motor DM impedance and mode transformation. First, the transmission line model of an induction motor is described based on the scattering (S) parameter measurements of each phase of the motor. It offers the flexibility to emulate different types of stator winding faults at specific locations and various severities, such that the impacts of the faults on the motor DM impedance can be easily estimated. Second, a test setup is proposed to quantify the CM-to-DM transformation due to the stator winding faults. The findings of this study reveal that even the early stages of stator winding faults can result in significant changes in the DM noise.

Differential-Mode Noise Prediction and Cancellation for High-Power Thyristor Trigger Circuit

This article is to predict and cancel differential-mode (DM) noise for high-power thyristor (HPT) trigger circuits and improve the reliability of capacitive pulsed power supply (CPPS). A lumped model of HPT trigger circuit is developed for the DM noise prediction within a concerning frequency range. The generation mechanism and propagation path of the DM noise are systematically studied. To attenuate the DM noise, a DM filter is proposed and discussed. The component parameters of the filter are investigated to improve its DM noise suppression effect. The DM spectrum for the HPT trigger circuit and the insertion losses of the DM filter are simulated and analyzed. Ultimately, DM spectrum tests are carried out. Both the simulated and measured results validate the theoretical analysis.

Design of a Modified Single-Stage and Multistage EMI Filter to Attenuate Common-Mode and Differential-Mode Noises in SiC Inverter

The SiC inverter switching at high frequencies introduces increased common-mode (CM) and differential-mode (DM) electromagnetic interference (EMI) issues, such as shaft voltage, bearing currents, insulation degradation, and poor current quality in the motor. These EMI issues are commonly addressed with EMI filters employing CM and DM inductors. The increased volume and poor performance of a CM inductor designed for SiC inverter switching at high frequency require a modified EMI filter design procedure for enhanced performance and volume minimization. In this work, three EMI filters are presented with modified design procedures. A single-stage EMI filter is designed by incorporating a DM filter offering an equal attenuation to DM and CM noise at switching frequency. Here, the additional CM attenuation demand is fulfilled by a marginal value of the CM inductor, while, in multistage EMI filters, the required CM attenuation is split between the two stages. The multistage EMI filter 1 is designed using an additional CM inductor and existing load capacitance as the second stage, whereas the multistage EMI filter 2 is designed with a lesser value of CM inductance to provide CM attenuation over the entire conducted EMI frequency range. The modified EMI filters are tested on an SiC inverter operating at 200 kHz.

Electromagnetic Interference Filter Design for a 100 kW Silicon Carbide Photovoltaic Inverter Without Switching Harmonics Filter

The design of electromagnetic interference (EMI) filter with smaller size and lightweight for a high efficiency and high power density 100 kW SiC five-level T-type (5LT2) photovoltaic (PV) inverter becomes more challenging due to the increased EMI noise resulted by high switching frequency, fast switching transients, and the removal of LCL filter. This paper proposes an unbalanced Wheatstone bridge and a two-stage notch filter to attenuate the increased common mode (CM) and differential mode (DM) noise respectively. The conventional Wheatstone bridge will suffer size and weight penalty for 100 kW PV converter due to the high parasitic capacitance of the 100 kW PV panel. An unbalanced Wheatstone bridge with a one-stage LC filter is therefore developed to address this issue and reduce the total CM inductance. The proposed two-stage notch filter is designed to achieve high attenuation, solve its parameter variation issue and help reduce the size and weight of DM filter. The total weight of the designed EMI filter for this 100 kW PV inverter is 3.54 kg. The measured conducted EMI spectrum of the 100 kW SiC PV inverter with and without proposed EMI filter are provided to validate the effectiveness of the EMI filter design.